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Index: head/sys/vm/uma_core.c
===================================================================
--- head/sys/vm/uma_core.c
+++ head/sys/vm/uma_core.c
@@ -1830,6 +1830,39 @@
return (slab_ipers_hdr(size, rsize, UMA_SLAB_SIZE, true));
}
+struct keg_layout_result {
+ u_int format;
+ u_int slabsize;
+ u_int ipers;
+ u_int eff;
+};
+
+static void
+keg_layout_one(uma_keg_t keg, u_int rsize, u_int slabsize, u_int fmt,
+ struct keg_layout_result *kl)
+{
+ u_int total;
+
+ kl->format = fmt;
+ kl->slabsize = slabsize;
+
+ /* Handle INTERNAL as inline with an extra page. */
+ if ((fmt & UMA_ZFLAG_INTERNAL) != 0) {
+ kl->format &= ~UMA_ZFLAG_INTERNAL;
+ kl->slabsize += PAGE_SIZE;
+ }
+
+ kl->ipers = slab_ipers_hdr(keg->uk_size, rsize, kl->slabsize,
+ (fmt & UMA_ZFLAG_OFFPAGE) == 0);
+
+ /* Account for memory used by an offpage slab header. */
+ total = kl->slabsize;
+ if ((fmt & UMA_ZFLAG_OFFPAGE) != 0)
+ total += slabzone(kl->ipers)->uz_keg->uk_rsize;
+
+ kl->eff = UMA_FRAC_FIXPT(kl->ipers * rsize, total);
+}
+
/*
* Determine the format of a uma keg. This determines where the slab header
* will be placed (inline or offpage) and calculates ipers, rsize, and ppera.
@@ -1843,15 +1876,14 @@
static void
keg_layout(uma_keg_t keg)
{
+ struct keg_layout_result kl = {}, kl_tmp;
+ u_int fmts[2];
u_int alignsize;
- u_int eff;
- u_int eff_offpage;
- u_int format;
- u_int ipers;
- u_int ipers_offpage;
+ u_int nfmt;
u_int pages;
u_int rsize;
u_int slabsize;
+ u_int i, j;
KASSERT((keg->uk_flags & UMA_ZONE_PCPU) == 0 ||
(keg->uk_size <= UMA_PCPU_ALLOC_SIZE &&
@@ -1866,8 +1898,6 @@
PRINT_UMA_ZFLAGS));
alignsize = keg->uk_align + 1;
- format = 0;
- ipers = 0;
/*
* Calculate the size of each allocation (rsize) according to
@@ -1877,10 +1907,7 @@
rsize = MAX(keg->uk_size, UMA_SMALLEST_UNIT);
rsize = roundup2(rsize, alignsize);
- if ((keg->uk_flags & UMA_ZONE_PCPU) != 0) {
- slabsize = UMA_PCPU_ALLOC_SIZE;
- pages = mp_maxid + 1;
- } else if ((keg->uk_flags & UMA_ZONE_CACHESPREAD) != 0) {
+ if ((keg->uk_flags & UMA_ZONE_CACHESPREAD) != 0) {
/*
* We want one item to start on every align boundary in a page.
* To do this we will span pages. We will also extend the item
@@ -1892,23 +1919,22 @@
slabsize = rsize * (PAGE_SIZE / alignsize);
slabsize = MIN(slabsize, rsize * SLAB_MAX_SETSIZE);
slabsize = MIN(slabsize, UMA_CACHESPREAD_MAX_SIZE);
- pages = howmany(slabsize, PAGE_SIZE);
- slabsize = ptoa(pages);
+ slabsize = round_page(slabsize);
} else {
/*
- * Choose a slab size of as many pages as it takes to represent
- * a single item. We will then try to fit as many additional
- * items into the slab as possible. At some point, we may want
- * to increase the slab size for awkward item sizes in order to
- * increase efficiency.
+ * Start with a slab size of as many pages as it takes to
+ * represent a single item. We will try to fit as many
+ * additional items into the slab as possible.
*/
- pages = howmany(keg->uk_size, PAGE_SIZE);
- slabsize = ptoa(pages);
+ slabsize = round_page(keg->uk_size);
}
+ /* Build a list of all of the available formats for this keg. */
+ nfmt = 0;
+
/* Evaluate an inline slab layout. */
if ((keg->uk_flags & (UMA_ZONE_NOTOUCH | UMA_ZONE_PCPU)) == 0)
- ipers = slab_ipers_hdr(keg->uk_size, rsize, slabsize, true);
+ fmts[nfmt++] = 0;
/* TODO: vm_page-embedded slab. */
@@ -1917,65 +1943,91 @@
* asked to not go to the VM for buckets. If we do this we
* may end up going to the VM for slabs which we do not
* want to do if we're UMA_ZFLAG_CACHEONLY as a result
- * of UMA_ZONE_VM, which clearly forbids it.
+ * of UMA_ZONE_VM, which clearly forbids it. In those cases,
+ * evaluate a pseudo-format called INTERNAL which has an inline
+ * slab header and one extra page to guarantee that it fits.
+ *
+ * Otherwise, see if using an OFFPAGE slab will improve our
+ * efficiency.
*/
- if ((keg->uk_flags &
- (UMA_ZFLAG_INTERNAL | UMA_ZFLAG_CACHEONLY)) != 0) {
- if (ipers == 0) {
- /* We need an extra page for the slab header. */
- pages++;
- slabsize = ptoa(pages);
- ipers = slab_ipers_hdr(keg->uk_size, rsize, slabsize,
- true);
- }
- goto out;
- }
+ if ((keg->uk_flags & (UMA_ZFLAG_INTERNAL | UMA_ZFLAG_CACHEONLY)) != 0)
+ fmts[nfmt++] = UMA_ZFLAG_INTERNAL;
+ else
+ fmts[nfmt++] = UMA_ZFLAG_OFFPAGE;
/*
- * See if using an OFFPAGE slab will improve our efficiency.
- * Only do this if we are below our efficiency threshold.
+ * Choose a slab size and format which satisfy the minimum efficiency.
+ * Prefer the smallest slab size that meets the constraints.
*
- * XXX We could try growing slabsize to limit max waste as well.
- * Historically this was not done because the VM could not
- * efficiently handle contiguous allocations.
+ * Start with a minimum slab size, to accommodate CACHESPREAD. Then,
+ * for small items (up to PAGE_SIZE), the iteration increment is one
+ * page; and for large items, the increment is one item.
*/
- eff = UMA_FRAC_FIXPT(ipers * rsize, slabsize);
- ipers_offpage = slab_ipers_hdr(keg->uk_size, rsize, slabsize, false);
- eff_offpage = UMA_FRAC_FIXPT(ipers_offpage * rsize,
- slabsize + slabzone(ipers_offpage)->uz_keg->uk_rsize);
- if (ipers == 0 || (eff < UMA_MIN_EFF && eff < eff_offpage)) {
- CTR5(KTR_UMA, "UMA decided we need offpage slab headers for "
- "keg: %s(%p), minimum efficiency allowed = %u%%, "
- "old efficiency = %u%%, offpage efficiency = %u%%",
- keg->uk_name, keg, UMA_FIXPT_PCT(UMA_MIN_EFF),
- UMA_FIXPT_PCT(eff), UMA_FIXPT_PCT(eff_offpage));
- format = UMA_ZFLAG_OFFPAGE;
- ipers = ipers_offpage;
+ i = (slabsize + rsize - keg->uk_size) / MAX(PAGE_SIZE, rsize);
+ KASSERT(i >= 1, ("keg %s(%p) flags=0x%b slabsize=%u, rsize=%u, i=%u",
+ keg->uk_name, keg, keg->uk_flags, PRINT_UMA_ZFLAGS, slabsize,
+ rsize, i));
+ for ( ; ; i++) {
+ slabsize = (rsize <= PAGE_SIZE) ? ptoa(i) :
+ round_page(rsize * (i - 1) + keg->uk_size);
+
+ for (j = 0; j < nfmt; j++) {
+ /* Only if we have no viable format yet. */
+ if ((fmts[j] & UMA_ZFLAG_INTERNAL) != 0 &&
+ kl.ipers > 0)
+ continue;
+
+ keg_layout_one(keg, rsize, slabsize, fmts[j], &kl_tmp);
+ if (kl_tmp.eff <= kl.eff)
+ continue;
+
+ kl = kl_tmp;
+
+ CTR6(KTR_UMA, "keg %s layout: format %#x "
+ "(ipers %u * rsize %u) / slabsize %#x = %u%% eff",
+ keg->uk_name, kl.format, kl.ipers, rsize,
+ kl.slabsize, UMA_FIXPT_PCT(kl.eff));
+
+ /* Stop when we reach the minimum efficiency. */
+ if (kl.eff >= UMA_MIN_EFF)
+ break;
+ }
+
+ if (kl.eff >= UMA_MIN_EFF ||
+ slabsize >= SLAB_MAX_SETSIZE * rsize ||
+ (keg->uk_flags & (UMA_ZONE_PCPU | UMA_ZONE_CONTIG)) != 0)
+ break;
}
-out:
+ pages = atop(kl.slabsize);
+ if ((keg->uk_flags & UMA_ZONE_PCPU) != 0)
+ pages *= mp_maxid + 1;
+
+ keg->uk_rsize = rsize;
+ keg->uk_ipers = kl.ipers;
+ keg->uk_ppera = pages;
+ keg->uk_flags |= kl.format;
+
/*
* How do we find the slab header if it is offpage or if not all item
* start addresses are in the same page? We could solve the latter
* case with vaddr alignment, but we don't.
*/
- if ((format & UMA_ZFLAG_OFFPAGE) != 0 ||
- (ipers - 1) * rsize >= PAGE_SIZE) {
+ if ((keg->uk_flags & UMA_ZFLAG_OFFPAGE) != 0 ||
+ (keg->uk_ipers - 1) * rsize >= PAGE_SIZE) {
if ((keg->uk_flags & UMA_ZONE_NOTPAGE) != 0)
- format |= UMA_ZFLAG_HASH;
+ keg->uk_flags |= UMA_ZFLAG_HASH;
else
- format |= UMA_ZFLAG_VTOSLAB;
+ keg->uk_flags |= UMA_ZFLAG_VTOSLAB;
}
- keg->uk_ipers = ipers;
- keg->uk_rsize = rsize;
- keg->uk_flags |= format;
- keg->uk_ppera = pages;
+
CTR6(KTR_UMA, "%s: keg=%s, flags=%#x, rsize=%u, ipers=%u, ppera=%u",
- __func__, keg->uk_name, keg->uk_flags, rsize, ipers, pages);
+ __func__, keg->uk_name, keg->uk_flags, rsize, keg->uk_ipers,
+ pages);
KASSERT(keg->uk_ipers > 0 && keg->uk_ipers <= SLAB_MAX_SETSIZE,
("%s: keg=%s, flags=0x%b, rsize=%u, ipers=%u, ppera=%u", __func__,
- keg->uk_name, keg->uk_flags, PRINT_UMA_ZFLAGS, rsize, ipers,
- pages));
+ keg->uk_name, keg->uk_flags, PRINT_UMA_ZFLAGS, rsize,
+ keg->uk_ipers, pages));
}
/*

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